Kullberg, Ann. Colored Pencil Portraits Step by Step. Cinncinatti: North Light Books, 1998. -Ann Kullberg's technique of vertical lines is rather tedious but this books demonstrates color well.
Hammond, Lee. How to Draw Lifelike Portraits from Photographs. Cinncinatti: Northern Light Books, 1995. -This is an excellent totorial that focus on realistic drawing in pencil. It's great for novice and intermediate artists.
Hammond, Lee. How to Draw Portraits in Colored Pencil from Photographs. Cinncinatti: Northern Light Books, 1997. -Same quality tutorial-wise, but this time, in color.
Beckett, Sister Wendy. The Story of Painting. London: Dorling Kindersley, 1994. A great book covers the history of paintings, especially those after the gothic, in detail. Great interpretations and colored photos.
Croix, Horst de la and Richard G. Tansey. Gardner's Art Through the Ages.
New York: Harcourt Brace Jovanovich, 1986. This book was orginally written
by Helen Gardner in 1926, and has been often used with college curriculms
and has been a favorite in classrooms accross America.